After a shameful witch hunt that mindlessly smeared the reputations of people guilty of nothing more than attending the Boston Marathon, Reddit has done the right thing.

On Monday, Erik Martin, general manager of the social media website, apologized fully for the debacle in which Reddit's amateur sleuths set out to determine, in full view of the world, who was responsible for the marathon bombing.

In the process, Reddit users circled the faces of people in pictures of the marathon crowd, pinpointing them as suspects, often based on nothing more than that they were wearing backpacks.

The nadir of the ill-conceived "let's play detective" fiasco came when a Redditor cruelly singled out Brown University student Sunil Tripathi, missing since last month, as the culprit.

In an awful week, this was an additional disaster that absolutely no one needed.

Why anyone thought this experiment in citizen law enforcement was a good idea is hard to imagine. But at least Martin, unlike some old-media institutions whose coverage went awry, had the courage to own up fully to the site's misdeeds.

In a post on Reddit called "Reflections on the Recent Boston Crisis," Martin began by citing some of the site's positive contributions during the tragedy. He added, "However, though started with noble intentions, some of the activity on Reddit fueled online witch hunts and dangerous speculation which spiraled into very negative consequences for innocent parties. The Reddit staff and the millions of people on Reddit around the world deeply regret that this happened."

Bill Iffrig, 78, lies on the ground as police officers react to a second explosion at the finish line of the Boston Marathon on April 15.(Photo: John Tlumacki, AP)

Martin paid special attention in the apology to Tripathi and his family.

"We have apologized privately to the family of missing college student Sunil Tripathi, as have various users and moderators. We want to take this opportunity to apologize publicly for the pain they have had to endure. We hope that this painful event will be channeled into something positive and the increased awareness will lead to Sunil's quick and safe return home. We encourage everyone to join and show your support to the Tripathi family and their search."

And he expressed the hope that the site and its users would learn from their dreadful performance.

"After this week, which showed the best and worst of Reddit's potential, we hope that Boston will also be where Reddit learns to be sensitive of its own power," he wrote.